Curved glass and manufacturing method thereof

ABSTRACT

The present disclosure relates to curved cover glass used for a curved display, and a manufacturing method thereof. The present disclosure provides tempered glass comprising: glass including a curved area; and a low-reflection coating layer, coated on a surface of the glass, composed of a mixture of a binder and a hollow material, wherein the glass comprises potassium ions which penetrate up to a predetermined depth therein. According to the present disclosure, a low-reflection coating layer is formed prior to curved surface processing, and thus, the low-reflection coating layer can be uniformly formed even on areas having different curvatures. Thus, the present disclosure can minimize the color difference generated in curved glass due to low-reflection coating layers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2018/000789, filed on Jan. 17, 2018, which claims the benefit of earlier filing date and right of priority to U.S. Provisional Application No. 62/488,867, filed on Apr. 24, 2017, and Korean Application No. 10-2017-0121969, filed on Sep. 21, 2017, the contents of which are all hereby incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present disclosure relates to curved cover glass used in a curved display and a manufacturing method thereof.

BACKGROUND

A display may include a cover glass for protecting the display. The cover glass may be highly light-transmissive and non-fragile. Various strengthening tempering methods can be utilized to prevent the glass from being broken easily.

With development of display technologies, a curved display has begun to be developed, and accordingly, a demand for cover glass in a curved shape is increasing. Particularly, attempts have been made to apply the curved display to a vehicle or the like.

As an example of a glass tempering (strengthening) method, a chemical strengthening method may be utilized. For instance, cover glasses may be prepared by replacing sodium ions contained in glass with potassium ions through ion exchange. In some cases, where the glass is cooled in presence of relatively bulky potassium ions than sodium ions, strength of the glass can be increased while maintaining the same volume as before.

The chemical strengthening method may be useful for glass strengthening because it may not increase thickness of the glass and may not lower transparency of the glass.

In some cases, when chemically strengthened glass is exposed to a high temperature, the chemical strengthening effect may disappear. In these cases, high temperature processing may not be performed after the glass is chemically strengthened. In some cases, where the chemical strengthening proceeds is performed in a manner of penetrating potassium ions into the glass, the chemical strengthening may not be performed after a coating layer is formed on the glass. In these cases, the chemical strengthening process is carried out after curving, and the coating layer is applied after the chemical strengthening.

In some examples, where the curved glass is applied to a vehicle or the like, a low-reflection coating layer may be utilized to prevent the driver's view from being disturbed. The low-reflection coating layer absorbs light that is externally introduced, thereby preventing the cover glass from reflecting light and disturbing the driver's view.

In some cases, where the low-reflection coating layer may be broken at high temperatures and interfere with the chemical strengthening, the coating layer is formed after the curving and the chemical strengthening. In some cases, when the coating layer is formed on a curved region, the thickness of the coating layer may vary depending on a curvature of the curved region. In addition, when the coating layer is formed on the curved region, uniformity of the coating layer may be lowered as compared with a case where the coating layer is formed on a planar region. This may cause a color difference between the planar region and the curved region. This may give users a sense of difference.

The present disclosure suggests a curved glass with a low-reflection coating layer, and a manufacturing method thereof.

SUMMARY

The present disclosure describes tempered glass having a curved surface, on which a low-reflection coating layer is uniformly formed on a curved region, and a manufacturing method thereof.

The present disclosure also describes tempered glass having a curved surface, capable of minimizing a color difference between regions having different curvatures, and a manufacturing method thereof.

The present disclosure further describes a coating layer, irrespective of a glass area, by switching low-reflection coating treatment to a coating method other than dry deposition.

According to one aspect of the subject matter described in this application, tempered glass includes a glass part having a curved region; and a low-reflection coating layer coated on a surface of the glass part, where the low-reflection coating layer includes a mixture of a binder and a hollow material. The glass part includes potassium ions penetrated into the glass part through the low-reflection coating layer and the surface of the glass part by a predetermined depth.

Implementations according to this aspect may include one or more of the following features. For example, a content ratio of the hollow material may be higher at an inner portion of the low-reflection coating layer than at an outer portion of the low-reflection coating layer. In some examples, the binder may include tetraethyl orthosilicate and trimethoxy-methylsilane that are polymerized together.

In some implementations, wherein the glass part may have a first region having a first curvature and a second region having a second curvature different from the first curvature. In some examples, the first region and the second region have a color difference (ΔE*ab) less than or equal to two. In some examples, the low-reflection coating layer may have a first area coated on the first region and a second area coated on the second region, and a thickness difference between the first area and the second area may be less than or equal to 10% of a thickness of the first area or the second area.

In some examples, an average molecular weight of the binder may be 1500 to 3500. In some examples, an average particle size of the hollow material may be 60 to 90 nm. In some examples, the low-reflection coating layer may be a single layer. In some examples, the potassium ions may be penetrated into the glass part by a depth of 30 to 50 um from the surface of the glass part. In some examples, a thickness of the low-reflection coating layer may be 100 to 150 nm from the surface of the glass part.

According to another aspect, a method for manufacturing tempered glass may include: preparing a binder polymer comprising a first monomer and a second monomer; preparing a low-reflection coating solution by mixing and polymerizing the binder polymer and a hollow material; coating the low-reflection coating solution on a glass part that is flat, and plasticizing the glass part to thereby define a low-reflection coating layer on the glass part; molding the glass part coated with the low-reflection coating layer at a predetermined temperature to define a curved surface of the glass part; and penetrating potassium ions into the glass part based on molding the glass part to define the curved surface.

Implementations according to this aspect may include one or more of the following features or the features described above. For instance, preparing the binder polymer may include polymerizing tetraethyl orthosilicate and trimethoxy-methylsilane together. In some examples, molding the glass part may include molding the glass part to define a first region having a first curvature and a second region having a second curvature different from the first curvature.

In some implementations, the low-reflection coating layer has a first area coated on the first region and a second area coated on the second region, and a thickness difference between the first area and the second area is less than or equal to 10% of a thickness of the first area or the second area. In some implementations, penetrating potassium ions into the glass part may include applying a solution comprising potassium to the glass part coated with the low-reflection coating layer.

In some examples, an average molecular weight of the binder polymer is 1500 to 3500. In some examples, an average particle size of the hollow material is 60 to 90 nm.

In some implementations, applying the low-reflection coating layer may include applying a single layer of the low-reflection coating solution to the glass part. In some implementations, penetrating the potassium ions into the glass part may include penetrating the potassium ions into the glass part by a depth of 30 to 50 um from a surface of the glass part.

In some implementations, since the low-reflection coating layer does not interfere with chemical strengthening, it may be possible to form the low-reflection coating layer on a glass surface before the chemical strengthening. Accordingly, the low-reflection coating layer can be formed before the glass is curved, thereby enhancing uniformity of the low-reflection coating layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual view illustrating an example method for performing chemical strengthening and low-reflection coating on a curved glass in related art.

FIG. 2 is a conceptual view illustrating an example method of manufacturing tempered glass according to the present disclosure.

FIG. 3 is a conceptual view illustrating an example of a cross-section of tempered glass.

FIG. 4A is a cross-sectional photograph showing an example of tempered glass before chemical strengthening.

FIG. 4B is a cross-sectional photograph showing an example of tempered glass after chemical strengthening.

FIG. 5 is a graph showing an example of reflectance of tempered glass before and after chemical strengthening.

FIG. 6A is a graph showing an example of an element distribution of tempered glass chemically strengthened without a coating layer.

FIG. 6B is a graph showing an example of an element distribution of the tempered glass according to the present disclosure.

DETAILED DESCRIPTION

Description will now be given in detail according to exemplary implementations disclosed herein, with reference to the accompanying drawings. For the sake of brief description with reference to the drawings, the same or equivalent components may be provided with the same or similar reference numbers, and description thereof will not be repeated. In describing the present disclosure, if a detailed explanation for a related known function or construction is considered to unnecessarily divert the gist of the present disclosure, such explanation has been omitted but would be understood by those skilled in the art. The accompanying drawings are used to help easily understand the technical idea of the present disclosure and it should be understood that the idea of the present disclosure is not limited by the accompanying drawings. The idea of the present disclosure should be construed to extend to any alterations, equivalents and substitutes besides the accompanying drawings.

It will be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally only used to distinguish one element from another.

A singular representation may include a plural representation unless it represents a definitely different meaning from the context.

Terms such as “include” or “has” are used herein and should be understood that they are intended to indicate an existence of several components, functions or steps, disclosed in the specification, and it is also understood that greater or fewer components, functions, or steps may likewise be utilized.

A related art method of performing chemical strengthening on curved glass and forming a low-reflection coating layer will be described.

FIG. 1 is a conceptual view illustrating the related art method for performing chemical strengthening and low-reflection coating on curved glass.

According to the related art method, first, flat glass of a desired size is processed (S110), followed by forming (molding) the flat glass 110 into a curved shape (S120). The curved surface forming is performed at a high temperature of 600° C. or higher. As a result, when the chemical strengthening and low reflection coating are carried out before the curved surface forming, the chemical strengthening effect may disappear or the low-reflection coating layer may be broken during the curved surface forming.

Thereafter, in the related art method, the glass formed into the curved shape is chemically strengthened (S130). Chemical strengthening (tempering) is a method of increasing hardness of glass by penetrating potassium ions into the glass. When a coating layer is formed on a glass surface, it is difficult to penetrate the potassium ions. Due to this, the chemical strengthening is performed before forming the coating layer on the glass surface.

Finally, a low-reflection coating layer is formed on the chemically strengthened curved glass surface (S140). A deposition method is utilized to form a relatively uniform coating layer on a curved surface. However, even if such a deposition method is utilized, it is difficult to reduce a thickness difference of the coating layer deposited on a flat region and a curved region down to a predetermined level or lower. As a result, the curved region has a different color from the flat region.

The present disclosure provides a method of uniformly forming a low-reflection coating layer in performing chemical strengthening and low reflection coating on a curved glass. Hereinafter, a method of manufacturing a tempered glass according to the present disclosure will be described with reference to the accompanying drawings.

FIG. 2 is a conceptual view illustrating an example of a method of manufacturing tempered glass according to the present disclosure.

For example, the manufacturing method may include, preparing a glass part having a desired size (S210) and applying a low-reflection coating layer on the glass part (S220). The glass part may have a flat shape in S210 and S220.

In some implementations, the low-reflection coating layer 120 may be formed by applying a coating solution which is a mixture of a binder and a hollow material to a surface of the flat glass 110 and then performing a plasticization process.

In some examples, the hollow material may lower a reflectance of the coating layer. Specifically, the hollow material may lower the reflectance by lowering a refractive index in a manner of forming an air layer on the glass surface.

In some examples, the hollow material may be made of silica. Since the hollow silica made of silica may not be decomposed even at a high temperature of 600° C. or higher, the coating layer may not be broken when curved surface forming is performed after forming the low-reflection coating layer.

In some implementations, an average particle size of the hollow material may be 60 to 90 nm. The hollow silica having a particle size of 60 nm or smaller is practically difficult to be manufactured. If the particle size of the hollow silica exceeds 90 nm, it becomes similar to the thickness of the coating layer to be explained later, which makes it difficult to form the coating layer uniformly.

In some implementations, the binder may fix the hollow material to the glass. In some examples, the binder may be exposed to a high temperature of 600° C. or higher during the curved surface forming, and may be made of a material that is not broken at the temperature of 600° C. or higher. For example, the binder may be a silane-based binder. Specifically, the binder may be, for example, tetraethyl orthosilicate (TEOS), trimethoxy-methylsilane (MTMS), fluoro-silane, acryl-silane, and silazane.

In some implementations, a weight average molecular weight of the binder may be 1500 to 3500. In some cases, where the weight average molecular weight of the binder is smaller than 1500, viscosity of the coating solution may be lowered, the influence on foreign substances during coating may be increased, and intermolecular interaction may be weakened to deteriorate a coating property. In some cases, where the average molecular weight of the binder exceeds 3500, the viscosity may become high, smoothness of the coating layer may be lowered, and stability of the coating layer may be deteriorated.

In some implementations, two or more kinds of binders may be mixed for use. For example, a mixture of TEOS and MTMS may be utilized as the binder. In this case, the coating solution may be prepared by mixing monomers of TEOS and MTMS, primarily polymerizing the mixture of the monomers, and then mixing the polymerized mixture with the hollow material. When TEOS and MTMS are primarily polymerized and then mixed with the hollow material, binder molecules surround the surface of the hollow material. This may result in making a core-shell structure in which the hollow material is a core and the binder molecules form a shell. This core-shell structure allows the hollow material to spread evenly when applied to the glass surface. Further, since the binder always surrounds the hollow material, the content of the binder is greater at an edge of the low-reflection coating layer, and the content of the hollow material is greater at the center of the low-reflection coating layer. Accordingly, the present disclosure can protect the hollow material, which substantially functions to lower the reflectance, from an external impact or the like.

The coating solution in which the hollow material and the binder are mixed may be applied onto the surface of the flat glass, then followed by the plasticization process, thereby forming the low-reflection coating layer. Here, the plasticization may be carried out in a plasticization furnace at a temperature of 400 to 750° C. for 4 to 6 minutes.

In some implementations, the low-reflection coating layer may have a thickness of 100 to 150 nm. In some cases, where the thickness of the coating layer is thinner than 100 nm, an effect of reducing reflectance may be lowered. In some cases, where the thickness exceeds 150 nm, uniformity of the coating layer may be lowered and subsequent chemical strengthening may not be performed properly.

In some implementations, the low-reflection coating layer may be formed as a single layer so that potassium ions can pass through the coating layer.

In some implementations, a porosity of the low-reflection coating layer may be 30 to 70%. In some cases, where the porosity of the low-reflection coating layer is lower than 30%, a reflection suppressing effect may be hardly expected and potassium ions may be less likely to penetrate to the glass surface during chemical strengthening to be described later. In some cases, where the porosity of the coating layer exceeds 70%, durability of the coating layer may be excessively decreased.

In some implementations, the low-reflection coating layer formed in the aforementioned manner has reflectance of 1% or lower.

In some implementations, after the low-reflection coating layer is formed on the flat glass, the flat glass is subjected to curved surface forming (S230). The curved surface forming may be carried out in a press-molding manner at a temperature of 700 to 780° C. and by pressure of 0.005 to 0.006 MPa. However, the present disclosure is not limited thereto.

Since the hollow material and the binder according to the present disclosure are not decomposed at a temperature of 700 to 780° C., the low-reflection coating layer may not be broken even after the curved surface forming, and the uniform coating layer formed on the flat glass can be maintained as it is.

In some implementations, a radius of curvature of the curved glass may be 5 R or greater. However, the present disclosure is not limited to this, and the radius of curvature may vary depending on the thickness of the glass and the area of the glass.

Finally, chemical strengthening is performed after the curved surface forming (S240).

The chemical strengthening may be carried out by immersing the glass in a potassium nitrate (KNO₃) solution, which has been heated to a temperature of 380 to 435° C., for 2 to 8 hours. At this time, potassium ions penetrate into the glass due to a difference in potassium ion concentration between the glass and the solution. Thus, strength of the glass is improved.

The related art chemical strengthening is carried out in a manner that potassium ions penetrate into the glass by 30 μm or higher. In this case, the glass may have a CS of 750 MPa or higher. The low-reflection coating layer according to the present disclosure is formed in a thickness of 150 nm or thinner and has porosity of 30% or higher, which may facilitate the potassium ions to penetrate into the glass surface. That is, the low-reflection coating layer according to the present disclosure may not interfere with the movement of the potassium ions. Exemplary experiments will be described later.

In some implementations, since chemical strengthening is carried out in a high pH solution, the low-reflection coating layer, especially the hollow material, may be destroyed due to hydrolysis. When using the binder that TEOS and MTMS are primarily polymerized, the binder can surround the hollow material surface and protect the hollow material from a strong basic solution.

Hereinafter, a tempered glass produced by the above-described method will be described.

FIG. 3 is a conceptual view illustrating a cross-section of an example of tempered glass according to the present disclosure.

The tempered glass 100 manufactured by the manufacturing method described above includes a glass part 110 having curved regions, and a low-reflection coating layer coated on a surface of the glass and made of a mixture of a binder 121 and a hollow material 122. Potassium ions have penetrated to the glass part 110 by a predetermined depth.

In some implementations, where a binder that TEOS and MTMS have primarily polymerized is used during the tempered glass production process, the content of the hollow material contained in the low-reflection coating layer is higher at the edge of the low-reflection coating layer than that at the center of the low-reflection coating layer. This structure protects the hollow material from a strong basic solution during chemical strengthening and protects the hollow material from an external impact.

In some implementations, the tempered glass may include curved surfaces having different curvatures depending on the use thereof. For example, the glass may include a first region having a first curvature and a second region having a second curvature different from the first curvature. Here, when the curvature is zero, the region may be flat, and the glass according to the present disclosure may include a flat region.

In some implementations, since the tempered glass according to the present disclosure is curved after forming the coating layer on the flat glass, the thickness of the low-reflection coating layer coated on the first region, and the thickness of the low-reflection coating layer coated on the second region may be different by 10% or lower, based on the thickness of the low-reflection coating layer coated on the first region.

Accordingly, the tempered glass according to the present disclosure may have a color difference (CIELAB ΔE*ab) of 2 or smaller between the first region and the second region based on the first region. The color difference increases when a curvature difference between the two regions of the glass increases. A color difference ΔE*ab between a region having the maximum curvature and a region having the minimum curvature in the tempered glass according to the present disclosure is 2 or smaller. That is, in the tempered glass according to the present disclosure, the color difference between all the arbitrary regions becomes 2 or smaller.

In some implementations, a radius of curvature of the curved glass may be 5 R or greater. However, the present disclosure is not limited to this, and the radius of curvature may vary depending on the thickness of the glass and the area of the glass. That is, the tempered glass according to the present disclosure may have a curvature of up to ⅕R. Accordingly, the maximum curvature difference in the tempered glass according to the present disclosure may be ⅕R. In the tempered glass according to the present disclosure, the color difference ΔE*ab between two regions having the maximum curvature difference is 2 or smaller.

In some implementations, a penetration depth of potassium ions into the glass may be 30 to 50 μm. This is the same depth as the penetration depth of potassium ions when performing chemical strengthening in the absence of the coating layer. That is, according to the present disclosure, the same chemical strengthening effect as that of the related art can be obtained even if the chemical strengthening is performed after the formation of the coating layer.

Hereinafter, the present disclosure will be described in more detail with reference to Implementations and Experimental Examples. However, it should be construed that the scope and contents of the present disclosure are not limited by the following Implementations and Experimental Examples.

Implementation. Preparation of Tempered Glass

A tempered glass was prepared according to the aforementioned manufacturing method using a hollow silica, which had an average particle size of 73.29 nm and a dispersion degree of 0.031, as a hollow material and using a material, which was obtained by primarily polymerizing TEOS and MTMS, as a binder.

FIG. 4A is a cross-sectional photograph of an example of tempered glass before chemical strengthening, and FIG. 4B is a cross-sectional photograph of an example of tempered glass after chemical strengthening.

In the case of FIG. 4B, a wave pattern is generated on the glass, but this is a pattern generated during a glass cutting process. Even if the chemical strengthening is performed, the structure of the glass does not change as much as being visible to the naked eye.

Referring to FIGS. 4A and 4B, the coating layer is formed in the state where the binder surrounds the surface of the hollow material. Accordingly, the binder is mainly disposed at the edge of the coating layer, and the hollow material is mainly disposed at the center of the coating layer.

In some implementations, referring to FIG. 4B, the low-reflection coating layer has a thickness of 100 to 130 nm.

FIG. 5 illustrates an example of experimental measurement results of a reflectance of tempered glass.

When manufacturing the tempered glass according to the above implementation, reflectance was measured before and after the chemical strengthening.

FIG. 5 is a graph showing an example of a reflectance before and after chemical strengthening.

Referring to FIG. 5, the reflectance of the tempered glass after chemical strengthening is slightly reduced. That is, it can be understood that the hollow material contained in the low-reflection coating layer is not destroyed even if the chemical strengthening is performed.

In some implementations, referring to FIG. 5, the tempered glass according to the present disclosure has reflectance of 1% or lower at a wavelength of 500 nm or longer. That is, the tempered glass according to the present disclosure has reflectance of 1% or lower even at a thickness of 100 to 150 nm.

A color difference between the curved region and the flat region of the tempered glass was measured in experiments.

According to the measurement of the color difference between the curved region and the flat region of the tempered glass according to the present disclosure, ΔE*ab was 0.8. This is hardly distinguished with the naked eyes of a person. As a result, the tempered glass according to the present disclosure has little color difference caused by low reflection coating, so that it does not give the user a sense of foreign body.

In contrast, the color difference between the curved region and the flat region of the curved glass having the low-reflection coating layer formed by the related art deposition method was measured. According to the measurement in related art, ΔE*ab was 8, where the color of the flat region was purple, and the color of the curved region was yellow. This is a color difference which is possibly seen by a person.

A chemical tempering depth was measured in experiments.

Distribution of elements Na, Si, K according to the depth of the tempered glass produced in the implementation was measured. In some implementations, for comparison, the elemental distribution of the tempered glass for which the chemical strengthening has been performed in the absence of the coating layer was measured.

FIG. 6A is a graph showing an example of an element distribution of tempered glass which has been chemically strengthened without a coating layer, and FIG. 6B is a graph showing an example of an element distribution of the tempered glass according to the present disclosure.

Comparing FIGS. 6A and 6B, the tempered glass subjected to the chemical strengthening in the absence of the coating layer and the tempered glass according to the present disclosure show similar distribution of potassium according to the depth of each of the tempered glasses. As a result, the chemical strengthening effect similar to the related art can be obtained by the manufacturing method according to the present disclosure even if the chemical strengthening is performed.

It will be apparent to those skilled in the art that the present disclosure may be embodied in other specific forms without from the spirit or essential characteristics thereof.

Therefore, it should also be understood that the above-described implementations are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its scope as defined in the appended claims, Therefore, all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the appended claims. 

1. Tempered glass, comprising: a glass part having a curved region; and a low-reflection coating layer coated on a surface of the glass part, the low-reflection coating layer comprising a mixture consisting of a binder and a hollow material, wherein the glass part comprises potassium ions penetrated into the glass part through the low-reflection coating layer and the surface of the glass part by a predetermined depth.
 2. The tempered glass of claim 1, wherein a content ratio of the hollow material is higher at an inner portion of the low-reflection coating layer than at an outer portion of the low-reflection coating layer.
 3. The tempered glass of claim 2, wherein the binder comprises tetraethyl orthosilicate and trimethoxy-methylsilane that are polymerized together.
 4. The tempered glass of claim 1, wherein the glass part has a first region having a first curvature and a second region having a second curvature different from the first curvature.
 5. The tempered glass of claim 4, wherein the first region and the second region have a color difference (ΔE*ab) less than or equal to two.
 6. The tempered glass of claim 4, wherein the low-reflection coating layer has a first area coated on the first region and a second area coated on the second region, and wherein a thickness difference between the first area and the second area is less than or equal to 10% of a thickness of the first area or the second area.
 7. The tempered glass of claim 1, wherein an average molecular weight of the binder is 1500 to
 3500. 8. The tempered glass of claim 1, wherein an average particle size of the hollow material is 60 to 90 nm.
 9. The tempered glass of claim 1, wherein the low-reflection coating layer is a single layer.
 10. The tempered glass of claim 1, wherein the potassium ions are penetrated into the glass part by a depth of 30 to 50 um from the surface of the glass part.
 11. The tempered glass of claim 1, wherein a thickness of the low-reflection coating layer is 100 to 150 nm from the surface of the glass part.
 12. A method for manufacturing tempered glass, the method comprising: preparing a binder polymer comprising a first monomer and a second monomer; preparing a low-reflection coating solution by mixing and polymerizing the binder polymer and a hollow material; coating layer by coating the low-reflection coating solution on a glass part that is flat, and plasticizing the glass part to thereby define a low-reflection coating layer on the glass part; molding the glass part coated with the low-reflection coating layer at a predetermined temperature to define a curved surface of the glass part; and penetrating potassium ions into the glass part based on molding the glass part to define the curved surface.
 13. The method of claim 12, wherein preparing the binder polymer comprises polymerizing tetraethyl orthosilicate and trimethoxy-methylsilane together.
 14. The method of claim 12, wherein molding the glass part comprises molding the glass part to define a first region having a first curvature and a second region having a second curvature different from the first curvature.
 15. The method of claim 14, wherein the low-reflection coating layer has a first area coated on the first region and a second area coated on the second region, and wherein a thickness difference between the first area and the second area is less than or equal to 10% of a thickness of the first area or the second area.
 16. The method of claim 14, wherein penetrating potassium ions into the glass part comprises applying a solution comprising potassium to the glass part coated with the low-reflection coating layer.
 17. The method of claim 12, wherein an average molecular weight of the binder polymer is 1500 to
 3500. 18. The method of claim 12, wherein an average particle size of the hollow material is 60 to 90 nm.
 19. The method of claim 12, wherein applying the low-reflection coating layer comprises applying a single layer of the low-reflection coating solution to the glass part.
 20. The method of claim 12, wherein penetrating the potassium ions into the glass part comprises penetrating the potassium ions into the glass part by a depth of 30 to 50 um from a surface of the glass part. 